The ethnic violence in the Rwandan capital Kigali is now spreading throughout the country, aid officials have said.

Tens of thousands of people are believed to have died since Rwanda's president died in a suspicious plane crash on 6 April.

The killing has mainly been carried out by Hutu gangs, who blame Tutsi rebels for downing President Juvenal Habyarimana's plane in a rocket attack. The President of Burundi was also killed.

Witnesses in Kigali say Hutu soldiers have been hacking Tutsi civilians to death with machetes in the street.

Inciting slaughter

A spokesman for the International Committee of the Red Cross, Jean-Luc Thevoz, said hundreds of thousands of Rwandans had also been forced to leave their homes by the violence.

"The situation is catastrophic, not just in Kigali, but in the rest of Rwanda," he said.

About 3,600 rebels from the mainly Tutsi Rwanda Patriotic Front (RPF) have infiltrated the capital. The group has said it will continue to fight until the Hutu-dominated government stops the massacres.

The RPF is currently moving to take the city and has blown up a radio station that it said was broadcasting propaganda inciting Hutus to slaughter Tutsis.

The 420 Belgian United Nations peacekeepers present in Rwanda are expected to withdraw within the next few days. Ten of their number were killed by government troops when the fighting began 12 days ago.

The planned withdrawal follows a stalemate at the UN Security Council over how best to deal with the unfolding disaster.

In the last few hours, an official from the RPF met the Rwandan ambassador in the Ugandan capital Kampala to discuss ways of ending the violence.

But UN spokesman Moctar Gueye told reporters no accord had been reached.

"My impression is that the fighting is dying down in the capital. Unfortunately we have no ceasefire agreement for the time being," he said.